U.S. patent application number 17/608363 was filed with the patent office on 2022-07-21 for plating method, insoluble anode for plating, and plating apparatus.
The applicant listed for this patent is EBARA CORPORATION. Invention is credited to Hiroyuki Kanda, Mizuki Nagai, Akira Owatari, Naoki Shimomura, Shingo Yasuda.
Application Number | 20220228285 17/608363 |
Document ID | / |
Family ID | 1000006301965 |
Filed Date | 2022-07-21 |
United States Patent
Application |
20220228285 |
Kind Code |
A1 |
Kanda; Hiroyuki ; et
al. |
July 21, 2022 |
PLATING METHOD, INSOLUBLE ANODE FOR PLATING, AND PLATING
APPARATUS
Abstract
Provided are a plating method, an insoluble anode and a plating
apparatus capable of reducing consumption of an additive in a
plating solution, when plating a substrate including a via or a
hole for forming a through electrode. The plating method includes
the steps of preparing a substrate including a via or a hole for
forming a through electrode, preparing a plating solution tank that
is divided, by a diaphragm, into an anode tank in which an
insoluble anode is disposed and a cathode tank in which the
substrate is disposed, and electroplating the substrate with an
anode current density when plating the substrate in the plating
solution tank being equal to or more than 0.4 ASD and equal to or
less than 1.4 ASD.
Inventors: |
Kanda; Hiroyuki; (Tokyo,
JP) ; Shimomura; Naoki; (Tokyo, JP) ; Nagai;
Mizuki; (Tokyo, JP) ; Yasuda; Shingo; (Tokyo,
JP) ; Owatari; Akira; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EBARA CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
1000006301965 |
Appl. No.: |
17/608363 |
Filed: |
May 13, 2020 |
PCT Filed: |
May 13, 2020 |
PCT NO: |
PCT/JP2020/019040 |
371 Date: |
November 2, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/2885 20130101;
C25D 21/12 20130101; C25D 17/12 20130101; C25D 17/002 20130101;
C25D 7/123 20130101 |
International
Class: |
C25D 17/12 20060101
C25D017/12; C25D 17/00 20060101 C25D017/00; C25D 7/12 20060101
C25D007/12; H01L 21/288 20060101 H01L021/288; C25D 21/12 20060101
C25D021/12 |
Foreign Application Data
Date |
Code |
Application Number |
May 17, 2019 |
JP |
2019-093404 |
Claims
1. A plating method comprising the steps of: preparing a substrate
including a via or a hole for forming a through electrode;
preparing a plating solution tank that is divided, by a diaphragm,
into an anode tank in which an insoluble anode is disposed and a
cathode tank in which the substrate is disposed; and electroplating
the substrate with an anode current density when plating the
substrate in the plating solution tank being equal to or more than
0.4 ASD and equal to or less than 1.4 ASD.
2. The plating method according to claim 1, wherein the insoluble
anode includes a power supply point to be connected to a power
source, a ring electrode having a ring shape around the power
supply point, and a connection electrode connecting the power
supply point and the ring electrode.
3. The plating method according to claim 2, wherein the ring
electrode includes a first ring electrode having a first diameter,
and a second ring electrode having a second diameter smaller than
the first diameter.
4. The plating method according to claim 2, wherein the connection
electrode linearly connects the power supply point and the ring
electrode.
5. The plating method according to claim 2, wherein the insoluble
anode has a rotationally symmetric shape around the power supply
point.
6. The plating method according to claim 2, wherein a cover that
covers a region of the power supply point of the insoluble anode
facing the substrate is attached to the power supply point.
7. The plating method according to claim 2, wherein the insoluble
anode is held by an anode holder, the anode holder includes an
opening opened to face the substrate, and a size of the ring
electrode of the insoluble anode is smaller than a size of the
opening.
8. The plating method according to claim 1, wherein the diaphragm
is an ion exchange membrane or a neutral diaphragm.
9. An insoluble anode for plating that is disposed in a plating
solution tank for use in the plating, the insoluble anode for the
plating comprising: a power supply point to be connected to a power
source; a ring electrode having a ring shape around the power
supply point; and a connection electrode connecting the power
supply point and the ring electrode.
10. A plating apparatus comprising: a plating solution tank
configured to store a plating solution; the insoluble anode for
plating according to claim 9; and a diaphragm that divides the
plating solution tank into an anode tank in which the insoluble
anode is disposed and a cathode tank in which a substrate is
disposed.
Description
TECHNICAL FIELD
[0001] The present invention relates to a plating method, an
insoluble anode for plating, and a plating apparatus.
BACKGROUND ART
[0002] Heretofore, a wiring has been formed in a fine wiring
groove, hole or resist opening provided in a surface of a
semiconductor wafer or the like, and a bump (a protruding
electrode) to be electrically connected to an electrode of a
package or the like has been formed on the surface of the
semiconductor wafer or the like. As a method of forming this wiring
and bump, for example, an electroplating method, an evaporation
method, a printing method, a ball bump method or the like is known,
but with increase in an I/O number of semiconductor chips and for a
finer pitch, the electroplating method is becoming often used in
which miniaturization is possible and performance is relatively
stable.
[0003] A plating apparatus for use in the electroplating method
includes a substrate holder holding a substrate of a semiconductor
wafer or the like, an anode holder holding an anode, and a plating
solution tank that stores a plating solution containing a large
number of types of additives. When a substrate surface of the
semiconductor wafer or the like is plated in this plating
apparatus, the substrate holder is disposed to face the anode
holder in the plating solution tank. In this state, the substrate
and the anode are energized, and accordingly a plating film is
formed on the substrate surface. In addition, the additive has an
effect of accelerating or suppressing a film formation speed of the
plating film, an effect of improving film quality of the plating
film, and the like.
[0004] Heretofore, a soluble anode that dissolves in the plating
solution or an insoluble anode that does not dissolve in the
plating solution has been used as the anode. In a case where the
plating is performed by using the insoluble anode, oxygen is
generated by reaction between the anode and the plating solution.
The additive in the plating solution reacts with this oxygen and is
decomposed. There is a problem that, when the additive is
decomposed, the additive loses the above-described effects, and a
desired film cannot be obtained on the substrate surface (e.g., see
PTL 1). To prevent this problem, the additive may be added to the
plating solution as required to keep concentration of the additive
in the plating solution in a predetermined concentration or more.
However, the additive is expensive, and hence it is desirable to
inhibit the decomposition of the additive as much as possible.
[0005] Furthermore, a technology of forming a plurality of through
electrodes made of a metal such as copper and extending through the
substrate in an up-down direction in an interior of the substrate
is known as means for conducting between respective layers when
stacking a conductor substrate on each of multiple layers (e.g.,
see PTL 1). FIG. 14 is a diagram showing an example of
manufacturing a substrate including a through electrode. First, as
shown in FIG. 14A, a substrate W is prepared in which a plurality
of recesses 112 for through electrodes that open upward are formed
in an interior of a base material 110 made of silicon or the like,
for example, by a lithography and etching technology. Each of the
recesses 112 for the through electrodes has a diameter, for
example, from 1 to 100 .mu.m, especially from 10 to 20 .mu.m, and a
depth, for example, from 70 to 150 .mu.m. Then, a seed layer 114
made of copper or the like is formed as a power supply layer for
electroplating on the surface of the substrate W by sputtering or
the like.
[0006] Next, the surface of the substrate W is electroplated with
copper, and as shown in FIG. 14B, an interior of each recess 112
for the through electrode of the substrate W is filled with a
copper plating film 116, and the copper plating film 116 is
deposited on the surface of the seed layer 114.
[0007] Afterward, as shown in FIG. 14C, excessive portions of the
copper plating film 116 and seed layer 114 on the base material 110
are removed by chemical mechanical polishing (CMP) or the like, and
additionally, a back surface side of the base material 110 is
polished and removed until a bottom surface of the copper plating
film 116 with which the interior of the recess 112 for the through
electrode is filled is exposed to outside. Consequently, the
substrate W is completed in which a plurality of through electrodes
118 made of copper (the copper plating films 116) and extending
through the substrate in the up-down direction are included.
[0008] In the recess 112 for the through electrode, a ratio of a
depth to a diameter, that is an aspect ratio, is generally large,
and it usually takes long period of time to completely fill the
interior of the recess 112 for the through electrode having such a
large aspect ratio with the copper film (the plating film) formed
by electroplating without causing a defect such as a void in the
recess.
CITATION LIST
Patent Literature
[0009] PTL 1: Japanese Patent Laid-Open No. 7-11498
SUMMARY OF INVENTION
Technical Problem
[0010] Heretofore, a method of increasing a surface area of an
anode and decreasing an anode current density during plating has
been performed as a method of decreasing an amount of oxygen to be
generated around the anode to reduce consumption of an additive in
a plating solution. Here, when a substrate including a via or a
hole having a large aspect ratio for forming a through electrode is
plated, a current during plating is reduced so that a defect such
as a void is not caused. However, according to investigation by
present inventors, it has been found that the consumption of the
additive might increase even during the plating of the substrate in
which the through electrode is to be formed. More specifically,
according to the investigation by the present inventors, it has
been seen that, when the anode current density during the plating
is excessively small, the generation of oxygen decreases, but
instead, generation of hypochlorous acid increases, and
decomposition of the additive is accelerated due to effect of
increased hypochlorous acid.
[0011] Furthermore, in a case where the surface area of the anode
is changed to regulate the anode current density to reduce the
consumption of the additive, there is concern that, when the
surface area of the anode is simply changed, uniformity of plating
formed on the substrate might be impaired.
[0012] The present invention has been developed in view of the
above problems, and one of objects thereof is to provide a plating
method, an insoluble anode and a plating apparatus capable of
reducing consumption of an additive in a plating solution, when
plating a substrate including a via or a hole for forming a through
electrode.
Solution to Problem
[0013] According to an embodiment of the present invention, a
plating method is provided, and the plating method includes the
steps of preparing a substrate including a via or a hole for
forming a through electrode, preparing a plating solution tank that
is divided, by a diaphragm, into an anode tank in which an
insoluble anode is disposed and a cathode tank in which the
substrate is disposed, and electroplating the substrate with an
anode current density when plating the substrate in the plating
solution tank being equal to or more than 0.4 ASD (A/cm.sup.2) and
equal to or less than 1.4 ASD. According to this plating method,
generation of oxygen and hypochlorous acid during the plating can
be inhibited, and consumption of an additive in a plating solution
can be reduced.
[0014] According to another embodiment of the present invention, an
insoluble anode for plating that is disposed in a plating solution
tank for use in the plating is provided, and the insoluble anode
includes a power supply point to be connected to a power source, a
ring electrode having a ring shape around the power supply point,
and a connection electrode connecting the power supply point and
the ring electrode. According to this insoluble anode for plating,
generation of oxygen and hypochlorous acid during the plating can
be inhibited, and consumption of an additive in a plating solution
can be reduced. Furthermore, in-plane uniformity of plating formed
on the substrate can be improved.
BRIEF DESCRIPTION OF DRAWINGS
[0015] FIG. 1 is a schematic view showing a plating apparatus
according to a first embodiment;
[0016] FIG. 2 is a plan view of an anode holder according to the
present embodiment;
[0017] FIG. 3 is a side cross-sectional view of an anode holder 60
taken along the 3-3 line shown in FIG. 2;
[0018] FIG. 4 is an exploded perspective view of the anode holder
in a state where a holder base cover is removed;
[0019] FIG. 5 is a plan view of the anode holder in the state where
the holder base cover is removed;
[0020] FIG. 6 is a flowchart showing an example of a plating method
in the present embodiment;
[0021] FIG. 7 is a view showing a first example of an anode in the
present embodiment;
[0022] FIG. 8 is a view showing a second example of the anode in
the present embodiment;
[0023] FIG. 9 is a view showing a third example of the anode in the
present embodiment;
[0024] FIG. 10 is a view showing a fourth example of the anode in
the present embodiment;
[0025] FIG. 11 is a view showing a fifth example of the anode in
the present embodiment;
[0026] FIG. 12 is a view showing a sixth example of the anode in
the present embodiment;
[0027] FIG. 13 is a schematic view showing a plating apparatus
according to a second embodiment; and
[0028] FIG. 14 is a view showing an example of manufacturing of a
substrate including a through electrode.
DESCRIPTION OF EMBODIMENTS
[0029] Hereinafter, embodiments of a plating method, an insoluble
anode for plating and a plating apparatus according to the present
invention will be described with reference to the accompanying
drawings. In the accompanying drawings, the same or similar element
is denoted with the same or similar reference sign, and in
descriptions of the respective embodiments, a description
concerning the same or similar element may not be repeated. Also,
characteristics illustrated in the respective embodiments are also
applicable to another embodiment as long as the characteristics of
the embodiments are not contradictory to each other.
First Embodiment
[0030] FIG. 1 is a schematic view showing a plating apparatus
according to a first embodiment. As shown in FIG. 1, the plating
apparatus includes a plating solution tank 50 holding a plating
solution inside, an anode 40 disposed in the plating solution tank
50, an anode holder 60 holding the anode 40, and a substrate holder
18. The substrate holder 18 removably holds a substrate W such as a
wafer, and is configured to immerse the substrate W into the
plating solution in the plating solution tank 50. The plating
apparatus according to the present embodiment is an electroplating
apparatus that applies current through the plating solution to
plate a surface of the substrate W with a metal. As the anode 40,
used is an insoluble anode made of, for example, titanium coated
with iridium oxide or platinum that does not dissolve in the
plating solution.
[0031] The substrate W is, for example, a semiconductor substrate,
a glass substrate, or a resin substrate. The metal with which the
surface of the substrate W is plated is, for example, copper (Cu),
nickel (Ni), tin (Sn), Sn--Ag alloy, or cobalt (Co).
[0032] The anode 40 and the substrate W are arranged to extend in a
vertical direction, that is, so that plate surfaces of the anode 40
and the substrate W face in a horizontal direction and face each
other in the plating solution. The anode 40 is connected to a
positive electrode of a power source 90 via the anode holder 60,
and the substrate W is connected to a negative electrode of the
power source 90 via the substrate holder 18. When a voltage is
applied between the anode 40 and the substrate W, current flows to
the substrate W, and a metal film is formed on the surface of the
substrate W in the presence of the plating solution.
[0033] The plating solution tank 50 includes a plating solution
storage tank 52 in which the substrate W and the anode 40 are
arranged, and an overflow tank 54 disposed adjacent to the plating
solution storage tank 52. The plating solution in the plating
solution storage tank 52 flows over a side wall of the plating
solution storage tank 52 to flow into the overflow tank 54.
[0034] One end of a plating solution circulation line 58a is
connected to a bottom of the overflow tank 54, and the other end of
the plating solution circulation line 58a is connected to a bottom
of the plating solution storage tank 52. A circulation pump 58b, a
constant temperature unit 58c and a filter 58d are attached to the
plating solution circulation line 58a. The plating solution flows
over the side wall of the plating solution storage tank 52 to flow
into the overflow tank 54, and further flows from the overflow tank
54 through the plating solution circulation line 58a to return to
the plating solution storage tank 52. Thus, the plating solution
circulates between the plating solution storage tank 52 and the
overflow tank 54 through the plating solution circulation line
58a.
[0035] The plating apparatus further includes a regulation plate 14
that regulates a potential distribution on the substrate W, and a
paddle 16 that stirs the plating solution in the plating solution
storage tank 52. The regulation plate 14 is disposed between the
paddle 16 and the anode 40, and includes an opening 14a for
limiting an electric field in the plating solution. The paddle 16
is disposed in the vicinity of the surface of the substrate W held
by the substrate holder 18 in the plating solution storage tank 52.
The paddle 16 is made of, for example, titanium (Ti) or resin. The
paddle 16 reciprocates in parallel with the surface of the
substrate W, to stir the plating solution so that metal ions are
sufficiently and uniformly supplied to the surface of the substrate
W during the plating of the substrate W.
[0036] FIG. 2 is a plan view of the anode holder 60, FIG. 3 is a
side cross-sectional view of the anode holder 60 taken along the
3-3 line shown in FIG. 2, FIG. 4 is an exploded perspective view of
the anode holder 60 in a state where a holder base cover 63 is
removed, and FIG. 5 is a plan view of the anode holder 60 in the
state where the holder base cover 63 is removed. Note that FIG. 5
shows, for convenience, the anode holder 60 in a state where a grip
64-2 is transparent. Furthermore, FIGS. 4 and 5 show, for
convenience, the anode holder 60 in a state where the anode 40 is
removed. Further, in the present description, "up" and "down" refer
to an upward direction and a downward direction in a state where
the anode holder 60 is vertically housed in the plating solution
tank 50. Similarly, in the present description, "a front surface"
refers to a surface on a side on which the anode holder 60 faces
the substrate holder, and "a back surface" refers to a surface on a
side opposite to the front surface.
[0037] As shown in FIGS. 2 to 4, the anode holder 60 according to
the present embodiment includes a substantially rectangular holder
base 62 including an inner space 61 that houses the anode 40, a
pair of grips 64-1 and 64-2 formed in an upper part of the holder
base 62, and a pair of arms 70-1 and 70-2 similarly formed in the
upper part of the holder base 62. Also, the anode holder 60
includes the holder base cover 63 that partially covers a front
surface of the holder base 62, a diaphragm 66 disposed on a front
surface of the holder base cover 63 to cover the inner space 61,
and an outer edge mask 67 disposed on a front surface of the
diaphragm 66. Additionally, in the present embodiment, the inner
space 61 of the anode holder 60 corresponds to "an anode tank", and
an outer space corresponds to "a cathode tank".
[0038] As shown in FIGS. 2 and 5, the holder base 62 includes a
hole 71 extending from an outer surface of a lower part to the
inner space 61 of the holder base, and communicating with the inner
space 61. Also, the holder base 62 includes an air outlet 81 for
exhausting air of the inner space 61, between the grips 64-1 and
64-2 in the upper part of the holder base. When the holder base 62
is immersed into the plating solution, the plating solution flows
through the hole 71 into the inner space 61, and air of the inner
space 61 is exhausted from the air outlet 81. Furthermore, in a
case where the insoluble anode is used as the anode 40, oxygen
generated from the anode 40 during the plating is also exhausted
through the air outlet 81. The air outlet 81 is closed with a lid
83 formed so that the exhaust of air is not obstructed.
[0039] Also, as shown in FIG. 3, an annular opening 63a having a
diameter larger than a diameter of the anode 40 is formed in a
substantially central portion of the holder base cover (base body)
63. The holder base cover 63 forms the inner space 61 together with
the holder base 62. The diaphragm 66 is disposed on a front surface
of the opening 63a, to close the inner space 61. A diaphragm
retainer 68 is attached in front of an outer peripheral edge of the
diaphragm 66, and the outer edge mask 67 is disposed in front of
the diaphragm retainer 68. Also, an annular first sealing member 84
including, for example, an O-ring or the like is disposed along the
opening 63a in the front surface of the holder base cover 63. The
diaphragm 66 is pressed onto the first sealing member 84 by the
diaphragm retainer 68, to seal the opening 63a. That is, a gap
between the diaphragm 66 and the inner space 61 can be sealed with
the first sealing member 84. Consequently, the inner space 61 and
the outer space are divided by the diaphragm 66.
[0040] The diaphragm 66 is, for example, an ion exchange membrane
such as a cation exchange membrane, or a neutral diaphragm. During
plating, cations can pass through the diaphragm 66 from an anode
side to a cathode side while any additive in the plating solution
does not pass. A specific example of the diaphragm 66 is YUMICRON
(registered trademark) manufactured by Yuasa Membrane Systems Co.,
Ltd.
[0041] The outer edge mask 67 is a plate-shaped member including an
annular opening in a central portion, and is detachably attached to
a front surface of the diaphragm retainer 68. The outer edge mask
67 is disposed to control the electric field in the surface of the
anode 40 during the plating. The outer edge mask 67 may have a
diameter of the opening that is larger than an outer diameter of
the anode 40, and may have an outer shape smaller than an outer
shape of the anode 40. Alternatively, the anode holder 60 does not
have to include the outer edge mask 67.
[0042] The holder base cover 63 is fixed to the holder base 62 by
screw connection, welding or the like, and the holder base cover 63
is closely connected to the holder base 62. Alternatively, the
holder base cover 63 may be formed integrally with the holder base
62.
[0043] As shown in FIGS. 2, 4 and 5, the grips 64-1 and 64-2 are
coupled with the holder base 62 via couplings 62-1 and 62-2 formed
in the upper part of the holder base 62. The grips 64-1 and 64-2
are formed to extend from the couplings 62-1 and 62-2 toward a
center of the holder base 62. The grips 64-1 and 64-2 are gripped
with an unshown chuck, when the anode holder 60 is conveyed to the
plating solution tank 50.
[0044] An electrode terminal 82 for applying a voltage to the anode
40 is disposed in a lower part of the arm 70-1 extending outward
from the couplings 62-1 and 62-2. The electrode terminal 82 is
connected to the positive electrode of the power source 90, when
the anode holder 60 is housed in the plating solution tank. Also,
the anode holder 60 includes a power supply member 89 extending
from the electrode terminal 82 to a substantially central portion
of the inner space 61. The power supply member 89 is a
substantially plate-shaped conductive member, and electrically
connected to the electrode terminal 82.
[0045] As shown in FIG. 3, the anode 40 is fixed to a front surface
of the power supply member 89 with a fixing member 88 including,
for example, a screw and the like. Consequently, the voltage can be
applied from the power source 90 to the anode 40 via the electrode
terminal 82 and the power supply member 89.
[0046] An annular opening 62a for changing the anode 40 is formed
in a substantially central portion of the holder base 62, that is,
at a position corresponding to the fixing member 88. The opening
62a communicates with a back surface side of the inner space 61,
and is covered with a lid 86. On a back surface side of the holder
base 62, an annular second sealing member 85 including, for
example, an O-ring or the like is disposed along the opening 62a. A
gap between the opening 62a and the lid 86 is sealed with the
second sealing member 85.
[0047] The lid 86 is removed when the anode 40 is changed.
Specifically, for example, with elapse of useful life of the anode
40, an operator removes the lid 86, and removes the fixing member
88 via the opening 62a. The operator removes the outer edge mask 67
from the diaphragm retainer 68, and removes the anode 40 from the
inner space 61. Subsequently, the operator houses another anode 40
in the inner space 61, and fixes the anode 40 to the front surface
of the power supply member 89 with the fixing member 88 via the
opening 62a. Lastly, the operator seals the opening 62a with the
lid 86, and attaches the outer edge mask 67 to the diaphragm
retainer 68.
[0048] A weight 87 is attached to a back surface of the holder base
62. Consequently, the anode holder 60 can be prevented from
floating on a surface of water due to buoyancy, when the anode
holder 60 is immersed into the plating solution.
[0049] As shown in FIG. 5, the anode holder 60 further includes a
valve 91 configured to seal the hole 71, a spring 96 for biasing
the valve 91 to close the valve 91, a shaft 93 for transmitting
biasing force of the spring 96 to the valve 91, a push rod 95 as an
operation member that operates the valve 91 to open and close the
valve, and an intermediate member 94 for transmitting, to the shaft
93, force applied to the push rod 95.
[0050] The valve 91 is disposed in the holder base 62 so that the
hole 71 can be sealed on an inner side of the holder base 62. The
shaft 93 is disposed along an up-down direction in the holder base
62. The shaft 93 has one end coupled to the valve 91, and the other
end coupled to the spring 96. Consequently, the shaft 93 transmits
the biasing force of the spring 96 to the valve 91, and the valve
91 is biased so that the hole 71 is sealed with the valve 91 on the
inner side of the holder base 62.
[0051] Thus, the anode holder 60 includes the valve 91 that seals
the hole 71, so that the hole 71 can be sealed, after the anode
holder 60 is immersed into the plating solution to fill the inner
space 61 with the plating solution. Consequently, if oxygen,
hypochlorous acid or monovalent copper is generated in the vicinity
of the anode 40, proceeding of decomposition of the additive can be
inhibited, because the outer space and the inner space 61 are
divided. Alternatively, in the plating apparatus, the anode holder
60 may be disposed in the plating solution storage tank 52 in a
state where a base liquid is put in the plating solution storage
tank 52, the inner space 61 of the anode holder 60 may be filled
with the base liquid and then sealed, and a liquid containing the
additive may be put in the plating solution storage tank 52 to
prepare the plating solution in the outer space. In this case, the
inner space 61 of the anode holder 60 does not store the additive,
and hence consumption of the additive in the vicinity of the anode
40 can be reduced more. However, the present invention is not
limited to this example, and the anode holder 60 may be disposed in
the plating solution storage tank 52 in a state where the plating
solution containing the additive is put in the plating solution
storage tank 52, and the inner space 61 of the anode holder 60 may
be filled with the plating solution containing the additive and
then sealed.
[0052] Next, a description will be made as to a plating method of
the present embodiment with reference to FIG. 6. Note that in the
following description, steps are described in order for ease of a
description, but the plating method is not limited to the steps to
be executed in order as in FIG. 6 and the following description.
That is, the respective steps may be executed by changing the order
of the steps unless there is any contradiction.
[0053] In the plating method of the present embodiment, first, the
substrate W including the via or the hole for forming the through
electrode is prepared (S10). As an example, as shown in FIG. 14A,
the substrate W is prepared in which a plurality of recesses 112
for the through electrodes that open upward are formed in the base
material 110 made of silicon or the like, for example, by a
lithography and etching technology. Each recess 112 for the through
electrode has a diameter, for example, from 1 to 100 .mu.m,
preferably from 5 to 20 .mu.m, and a depth, for example, from 70 to
150 .mu.m. Note that in the substrate W, a hole extending through
the substrate in the up-down direction may be formed in place of or
in addition to the recesses (vias) for the through electrodes.
[0054] Subsequently, a plating solution tank is prepared (S20). In
the present embodiment, the plating solution tank 50 in the
above-described plating apparatus is prepared. The plating solution
tank 50 is divided, by the diaphragm 66, into the inner space 61
(the anode tank in which the anode 40 is disposed) and the outer
space (the cathode tank in which the substrate W is disposed).
[0055] Next, the anode 40 is designed and prepared (S30).
Specifically, the anode 40 is designed and prepared in terms of
size and shape so that current density in the anode 40
(hereinafter, referred to as "the anode current density)") when
plating the substrate W in the plating solution tank 50 is equal to
or more than 0.4 ASD (A/cm.sup.2) and equal to or less than 1.4
ASD. This is based on finding, according to investigation by the
present inventors, that the consumption of the additive in the
plating solution can be reduced especially when the anode current
density is equal to or more than 0.4 ASD and equal to or less than
1.4 ASD. That is, if the anode current density during plating is
large (e.g., in excess of 1.4 ASD), an amount of oxygen to be
generated around the anode 40 increases, and the consumption of the
additive in the plating solution increases. On the other hand, if
the anode current density during the plating is excessively small
(e.g., less than 0.4 ASD), an amount of hypochlorous acid to be
generated around the anode 40 increases, and the consumption of the
additive in the plating solution increases. Then, when the anode
current density during the plating is equal to or more than 0.4 ASD
and equal to or less than 1.4 ASD, the consumption of the additive
in the plating solution can be suitably reduced. Consequently, in a
process of S30, the anode 40 is designed and prepared based on the
substrate W or the like to be plated so that the anode current
density during the plating is equal to or more than 0.4 ASD and
equal to or less than 1.4 ASD. Here, it is preferable to design the
anode 40 so that the anode current density is equal to or more than
0.4 ASD, especially equal to or more than 0.5 ASD, or equal to or
more than 0.6 ASD. Also, it is preferable to design the anode 40 so
that the anode current density is equal to or less than 1.4 ASD,
especially equal to or less than 1.3 ASD, equal to or less than 1.2
ASD, equal to or less than 1.1 ASD, or equal to or less than 1.0
ASD.
[0056] As a specific example of the design of the anode 40, first,
a current amount (or a cathode current density) during the plating
is determined in accordance with an area and shape of the substrate
W. Here, in the present embodiment, the recesses 112 for the
through electrodes are formed in the substrate W. and hence a
comparatively small current amount is determined so that a defect
such as a void is not caused. The current amount during the plating
may only be set by using a known method. The setting does not form
core of the present invention, and hence a detailed description
will not be made. Then, the anode 40 is designed by determining,
based on the set current amount, the size and shape of the anode 40
so that the anode current density is a desired current density. A
preferable shape of the anode 40 for satisfying the current density
will be described later.
[0057] Then, the substrate W prepared in S10 and the anode 40
prepared in S30 are arranged in the plating solution tank 50
prepared in S20, and electroplating is performed at the anode
current density that is equal to or more than 0.4 ASD and equal to
or less than 1.4 ASD (S40). It is preferable that the anode current
density during the plating is equal to or more than 0.4 ASD,
especially equal to or more than 0.5 ASD, or equal to or more than
0.6 ASD. Also, it is preferable that the current density during the
plating is equal to or less than 1.4 ASD, especially equal to or
less than 1.3 ASD, equal to or less than 1.2 ASD, equal to or less
than 1.1 ASD, or equal to or less than 1.0 ASD. Thus, the anode
current density is set within a predetermined range, so that the
generation of oxygen and hypochlorous acid around the anode 40 can
be inhibited, and the consumption of the additive in the plating
solution can be reduced.
[0058] Next, a description will be made as to an example of the
specific shape of the anode 40 of the present embodiment. FIG. 7 is
a view showing a first example of the anode of the present
embodiment. An anode 40A shown in FIG. 7 includes a power supply
point 402 connected to the power source 90 via the anode holder 60,
a ring electrode 410 having a ring shape around the power supply
point, and a connection electrode 404 connecting the power supply
point 402 and the ring electrode 410.
[0059] The power supply point 402 is connected to the power supply
member 89 (see FIG. 4) of the anode holder 60. In the present
embodiment, the connection electrode 404 and the ring electrode 410
are not directly connected to the power supply member 89 of the
anode holder 60, but are connected via the power supply point 402.
However, the present invention is not limited to this example, and
at least parts of the connection electrode 404 and the ring
electrode 410 may be directly connected to the power supply member
89. The power supply point 402 is circular when viewed from front
(substrate W side), and a plurality of holes are formed to attach
the power supply point to the power supply member 89. However, the
power supply point 402 is not limited to this shape, as long as the
power supply point is configured to be connectable to the power
source 90.
[0060] The ring electrode 410 defines an outer edge of the anode
40A. It is preferable that an outer diameter of the ring electrode
410 is smaller than a diameter of the opening 63a of the anode
holder 60. It is also preferable that an outer shape of the ring
electrode 410 is substantially similar to an outer shape of the
substrate W. For example, it is preferable that when the substrate
W is circular, the ring electrode 410 is annular, and that when the
substrate W is quadrangular, the ring electrode 410 has a
quadrangular frame shape formed with four sides. In the example
shown in FIG. 7, the connection electrode 404 linearly connects the
power supply point 402 and the ring electrode 410. A plurality of
connection electrodes 404 are provided at respective predetermined
angles from the power supply point 402, and in the example shown in
FIG. 7, eight connection electrodes 404 are provided radially
around the power supply point 402. The ring electrode 410 and the
connection electrode 404 may have about the same cross-sectional
shape as a cross section that is a plane perpendicular to a
longitudinal direction. For example, each of the ring electrode 410
and the connection electrode 404 may have a cross section that is a
square, especially a square with each side being 1 mm, a square
with each side being 2 mm, or a square with each side being 3 mm.
However, the present invention is not limited to this example, and
the ring electrode 410 and the connection electrode 404 may have a
cross section that is, for example, rectangular, polygonal or
circular.
[0061] The anode 40 is formed into this shape, and accordingly,
when the plating is performed to form the through electrode in the
substrate W, the consumption of the additive in the plating
solution can be reduced by regulating the anode current density.
Furthermore, in-plane uniformity of plating formed on the substrate
W can be improved. Here, to improve the in-plane uniformity of the
plating formed on the substrate W, it is preferable that the anode
40 has a rotationally symmetric shape around the power supply point
402.
[0062] Subsequently, a description will be made as to a
modification of the anode 40. FIG. 8 is a view showing a second
example of the anode of the present embodiment. An anode 40B shown
in FIG. 8 is different from the anode 40A shown in FIG. 7 in the
ring electrode 410, and the anodes have the same shape except the
ring electrode 410. The anode 40B includes, as the ring electrode
410, a first ring electrode 410a that defines an outer edge of the
anode 40B, and a second ring electrode 410b having a diameter
smaller than a diameter of the first ring electrode 410a. The first
ring electrode 410a and the second ring electrode 410b are
concentrically arranged around the power supply point 402. The
first ring electrode 410a includes a configuration similar to a
configuration of the ring electrode 410 of the anode 40A shown in
FIG. 7, and is connected to the power supply point 402 via the
connection electrode 404. In the anode 40B, the connection
electrode 404 has one end connected to the power supply point 402,
and the other end connected to the first ring electrode 410a. Also,
the connection electrode 404 is connected to the second ring
electrode 410b in an intermediate portion between the one end and
the other end. Consequently, the second ring electrode 410b is
connected to the power supply point 402 via the connection
electrode 404. Each of the first ring electrode 410a and the second
ring electrode 410b may have about the same cross-sectional shape
as in the connection electrode 404, in the same manner as in the
ring electrode 410 of the anode 40A.
[0063] FIG. 9 is a view showing a third example of the anode of the
present embodiment. An anode 40C shown in FIG. 9 is different from
the anode 40A shown in FIG. 7 in the ring electrode 410, and the
anodes have the same shape except the ring electrode 410. The anode
40C includes, as the ring electrode 410, a first ring electrode
410a that defines an outer edge of the anode 40C, a second ring
electrode 410b having a diameter smaller than a diameter of the
first ring electrode 410a, and a third ring electrode 410c having a
diameter smaller than the diameter of the second ring electrode
410b. The first to third ring electrodes 410a to 410c are
concentrically arranged around the power supply point 402. The
first ring electrode 410a and the second ring electrode 410b have a
configuration similar to a configuration of the ring electrode of
the anode 40B shown in FIG. 8, and are connected to the power
supply point 402 via the connection electrode 404. In the anode
40C, the connection electrode 404 is connected to the second ring
electrode 410b and the third ring electrode 410c in an intermediate
portion. Consequently, the second ring electrode 410b and the third
ring electrode 410c are connected to the power supply point 402 via
the connection electrode 404. Each of the first to third ring
electrodes 410a to 410c may have about the same cross-sectional
shape as in the connection electrode 404, in the same manner as in
the ring electrode 410 of the anode 40A. Note that as shown in
FIGS. 7 to 9, the anode 40 is not limited to the anode including
one to three ring electrodes 410, and may include four or more ring
electrodes 410.
[0064] FIG. 10 is a view showing a fourth example of the anode of
the present embodiment. An anode 40D shown in FIG. 10 is different
from the anode 40A shown in FIG. 7 in the connection electrode 404,
and the anodes have the same shape except the connection electrode
404. The anode 40D includes, as the connection electrode 404, an
electrode extending in an up-down direction and a right-left
direction and connecting the power supply point 402 and the ring
electrode 410. That is, in the anode 40A shown in FIG. 7,
connection electrodes 404 are arranged radially from the power
supply point 402 in eight directions, but in the anode 40D shown in
FIG. 10, the connection electrodes 404 are arranged radially from
the power supply point 402 in four directions. Note that as shown
in FIGS. 7 and 10, the anode 40 is not limited to the anode
including the connection electrodes 404 arranged radially in eight
directions or four directions, and may include any number of
connection electrodes 404. Also, the anode 40 may include two or
more ring electrodes 410 regardless of the number of the connection
electrodes 404.
[0065] FIG. 11 is a view showing a fifth example of the anode of
the present embodiment. An anode 40E shown in FIG. 11 is different
from the anode 40A shown in FIG. 7 in the connection electrode 404,
and the anodes have the same shape except the connection electrode
404. The anode 40A described above and shown in FIG. 7 includes a
plurality of linear electrodes as the connection electrodes 404,
but in the anode 40E shown in FIG. 11, each of a plurality of
connection electrodes 404 has a curved shape. Also, in this case,
it is preferable that the connection electrodes 404 are formed so
that the anode 40E has a rotationally symmetric shape around the
power supply point 402. Note that also in the examples shown in
FIGS. 8 to 10, the connection electrode 404 may have a curved
shape.
[0066] FIG. 12 is a view showing a sixth example of the anode of
the present embodiment. An anode 40F shown in FIG. 12 is the same
as the anode 40A shown in FIG. 7 except that a cover 420 is
attached to the power supply point 402. The cover 420 covers a
front surface in the power supply point 402 (a surface facing the
substrate W) to improve the uniformity of the plating formed on the
substrate W. The cover 420 may be made of a highly insulating resin
such as polyvinyl chloride (PVC) or polypropylene (PP). In the
example shown in FIG. 12, the cover 420 includes a plate-shaped
part 421 having a circular shape with a diameter more than a
diameter of the power supply point 402, and a fitting part 422
protruding rearward from the plate-shaped part 421. The
plate-shaped part 421 is disposed to control an electric field on
an anode surface, and may have a size determined by simulation,
experiment or the like to improve the uniformity of the plating
formed on the substrate W. Also, the fitting part 422 is disposed
to attach the cover 420 to the power supply point 402. An inner
peripheral surface of the fitting part 422 has a shape
corresponding to a shape of an outer peripheral side surface of the
power supply point 402. Also, the fitting part 422 includes a
plurality of recesses corresponding to the connection electrodes
404 extending from the power supply point 402. According to this
configuration, the cover 420 can be attached by fitting the fitting
part 422 from front into the power supply point 402. However, the
present invention is not limited to this example, and the cover 420
may be attached to the power supply point 402 by use of a fastener
such as a screw, or an adhesive or the like. The cover 420 is
disposed to cover the power supply point 402 from the front, and
accordingly the uniformity of the plating formed on the substrate W
can be improved. Alternatively, the cover 420 may be attached to
the anodes 40B to 40E shown in FIGS. 8 to 11.
Second Embodiment
[0067] FIG. 13 is a schematic view showing a plating apparatus
according to a second embodiment. The plating apparatus according
to the second embodiment is different from the plating apparatus
according to the first embodiment in that a diaphragm 66 is not
attached to an anode holder 60, but is attached to an opening 14a
in a regulation plate 14. In the following description, a
description that overlaps with that of the first embodiment will
not be repeated.
[0068] In the plating apparatus according to the second embodiment,
a shield box 160 is disposed in a plating solution storage tank 52,
and accordingly, an interior of the plating solution storage tank
52 is divided into an anode tank 170 inside the shield box 160 and
a cathode tank 172 outside the shield box. In the example shown in
FIG. 13, the anode holder 60 holding an anode 40 and the regulation
plate 14 are arranged in the anode tank 170, and a paddle 16 and a
substrate holder 18 (cathode) are arranged in the cathode tank
172.
[0069] The shield box 160 includes an opening 160a at a position
corresponding to the opening 14a of the regulation plate 14. Also,
a tubular part that defines the opening 14a of the regulation plate
14 is fitted into the opening 160a of the shield box 160. According
to this configuration, the anode tank 170 communicates with the
cathode tank 172 through the opening 14a of the regulation plate
14. Then, in the second embodiment, the diaphragm 66 is attached to
the opening 14a of the regulation plate 14, and the anode tank 170
and the cathode tank 172 are divided by the diaphragm 66.
Alternatively, the diaphragm 66 may be attached from an anode tank
170 side in the regulation plate 14, or may be attached from a
cathode tank 172 side. Furthermore, the diaphragm 66 may be
attached to the regulation plate 14 by an arbitrary method, and is
attached to the regulation plate 14 by use of an annular diaphragm
retainer 68 as an example.
[0070] In the plating apparatus of the second embodiment, a plating
solution in the cathode tank 172 flows over a side wall of the
plating solution storage tank 52 to flow into an overflow tank 54.
On the other hand, the plating solution in the anode tank 170 is
configured not to overflow. Further, a liquid discharge line 190 in
which an on-off valve 186 is disposed is connected to the anode
tank 170. For example, when the diaphragm 66 is changed, the
plating solution (base liquid) in the anode tank 170 can be
discharged through the liquid discharge line 190.
[0071] Also, in the plating apparatus according to the second
embodiment, a base liquid supply line 158 is connected to a plating
solution circulation line 58a. The base liquid supply line 158 is
not intended to supply the plating solution to the plating solution
storage tank 52 during plating of a substrate W, but is used to
first supply the base liquid to the plating solution storage tank
52 for performing plating, that is, used only for so-called initial
make-up of an electrolytic bath. The base liquid supply line 158 is
provided with a first supply valve 151. Also, in the plating
apparatus of the second embodiment, a connection line 192 is
disposed to connect the plating solution circulation line 58a and
the liquid discharge line 190. The connection line 192 is provided
with a second supply valve 152. Further, the plating apparatus of
the second embodiment is provided with an additive supply line 159
for supplying an additive to the cathode tank 172. The additive
supply line 159 is provided with a third supply valve 153. Usually,
the first to third supply valves 151 to 153 are closed.
[0072] According to the plating apparatus of the second embodiment,
the first supply valve 151 and the second supply valve 152 are
opened only during the initial make-up of the electrolytic bath,
and the base liquid from the base liquid supply line 158 is
supplied through the liquid discharge line 190 and the plating
solution circulation line 58a into the anode tank 170 and the
cathode tank 172. Then, the third supply valve 153 is opened, to
supply the additive only to the cathode tank 172. According to this
configuration, the anode tank 170 does not store the additive, and
hence consumption of the additive in the vicinity of the anode 40
can be reduced.
[0073] In the plating apparatus of the second embodiment described
above, the plating solution storage tank 52 is divided into the
anode tank 170 and the cathode tank 172 by the shield box 160 and
the regulation plate 14. Then, the diaphragm 66 is disposed in the
opening 14a of the regulation plate 14. Also, in this
configuration, the substrate W is plated with the anode current
density being equal to or more than 0.4 ASD and equal to or less
than 1.4 ASD when plating the substrate W to form the through
electrode, in the same manner as in the plating apparatus of the
first embodiment. Consequently, generation of oxygen and
hypochlorous acid during the plating can be inhibited, and the
consumption of the additive in the plating solution can be
reduced.
[0074] The present embodiments described above can also be
described in aspects as follows.
[0075] [Aspect 1]
[0076] According to Aspect 1, a plating method is provided, and the
plating method includes the steps of preparing a substrate
including a via or a hole for forming a through electrode,
preparing a plating solution tank that is divided, by a diaphragm,
into an anode tank in which an insoluble anode is disposed and a
cathode tank in which the substrate is disposed, and electroplating
the substrate with an anode current density when plating the
substrate in the plating solution tank being equal to or more than
0.4 ASD and equal to or less than 1.4 ASD. According to this
plating method, generation of oxygen and hypochlorous acid during
the plating can be inhibited, and consumption of an additive in a
plating solution can be reduced.
[0077] [Aspect 2]
[0078] According to Aspect 2, in Aspect 1, the insoluble anode
includes a power supply point to be connected to a power source, a
ring electrode having a ring shape around the power supply point,
and a connection electrode connecting the power supply point and
the ring electrode. According to Aspect 2, in-plane uniformity of
plating formed on the substrate can be improved.
[0079] [Aspect 3]
[0080] According to Aspect 3, in Aspect 2, the ring electrode
includes a first ring electrode having a first diameter, and a
second ring electrode having a second diameter smaller than the
first diameter.
[0081] [Aspect 4]
[0082] According to Aspect 4, in Aspect 2 or 3, the connection
electrode linearly connects the power supply point and the ring
electrode.
[0083] [Aspect 5]
[0084] According to Aspect 5, in Aspects 2 to 4, the insoluble
anode has a rotationally symmetric shape around the power supply
point.
[0085] [Aspect 6]
[0086] According to Aspect 6, in Aspects 2 to 5, a cover that
covers a region of the power supply point of the insoluble anode
facing the substrate is attached to the power supply point.
According to Aspect 6, an electric field on an anode surface can be
controlled by the cover, and the in-plane uniformity of the plating
formed on the substrate can be improved.
[0087] [Aspect 7]
[0088] According to Aspect 7, in Aspects 2 to 6, the insoluble
anode is held by an anode holder, the anode holder includes an
opening opened to face the substrate, and a size of the ring
electrode of the insoluble anode is smaller than a size of the
opening.
[0089] [Aspect 8]
[0090] According to Aspect 8, in Aspects 1 to 7, the diaphragm is
an ion exchange membrane or a neutral diaphragm.
[0091] [Aspect 9]
[0092] According to Aspect 9, an insoluble anode for plating that
is disposed in a plating solution tank for use in the plating is
provided, and the anode includes a power supply point to be
connected to a power source, a ring electrode having a ring shape
around the power supply point, and a connection electrode
connecting the power supply point and the ring electrode. According
to Aspect 9, generation of oxygen and hypochlorous acid during the
plating can be inhibited, and the consumption of the additive in
the plating solution can be reduced. Furthermore, the in-plane
uniformity of the plating formed on the substrate can be
improved.
[0093] [Aspect 10]
[0094] According to Aspect 10, a plating apparatus is provided, and
includes a plating solution tank configured to store a plating
solution, the insoluble anode for plating according to Aspect 9,
and a diaphragm that divides the plating solution tank into an
anode tank in which the insoluble anode is disposed and a cathode
tank in which a substrate is disposed. According to Aspect 10, the
plating apparatus includes the anode for plating of Aspect 9, and
can exhibit effects similar to those of Aspect 9.
[0095] The embodiments of the present invention have been described
above based on several examples, but the above embodiments of the
present invention are described to facilitate understanding of the
present invention, and do not limit the present invention. The
present invention may be changed or modified without departing from
the scope, and needless to say, the present invention includes
equivalents to the invention. Also, in a range in which at least
some of the above-described problems can be solved or a range in
which at least some of effects are exhibited, any arbitrary
combination or omission of respective constituent components
described in the claims and description is possible.
[0096] The present application is based on and claims the benefit
of priority of Japanese Patent Application No. 2019-93404 filed on
May 17, 2019. All disclosed contents including the description,
claims, drawings and abstract of Japanese Patent Application No.
2019-93404 are entirely incorporated herein by reference. All
disclosure including the description, claims, drawings and abstract
of Japanese Patent Laid-Open No. 7-11498 (PTL 1) is entirely
incorporated herein by reference.
REFERENCE SIGNS LIST
[0097] 14 regulation plate [0098] 14a opening [0099] 16 paddle
[0100] 18 substrate holder [0101] 40 and 40A to 40F anode
(insoluble anode) [0102] 50 plating solution tank [0103] 52 plating
solution storage tank [0104] 54 overflow tank [0105] 60 anode
holder [0106] 61 inner space [0107] 62 holder base [0108] 63 holder
base cover [0109] 66 diaphragm [0110] 67 outer edge mask [0111] 68
diaphragm retainer [0112] 402 power supply point [0113] 404
connection electrode [0114] 410 ring electrode [0115] 410a first
ring electrode [0116] 410b second ring electrode [0117] 410c third
ring electrode [0118] 420 cover
* * * * *